In order to locate candidate genes related to flowering time, and to provide a basis for genetic improvement and flowering time of Brassica campestris, a natural population composed of 110 B. campestris was used as research materials. Flowering investigation and resequencing were performed on them. The high-quality SNP set obtained by resequencing was used for population evolutionary tree analysis, principal component analysis, population genetic structure analysis and a genome-wide association analysis. The observation results showed there were wide differences in flowering time between different types of B. campestris. The results of population structure analysis showed that 110 materials could be divided into two subgroups. The distribution within each phylogenetic tree was relatively concentrated, and the distribution between different subgroups was closely related to the geographical origin of the material. Genome-wide association analysis revealed that the average LD of the whole B. campestris attenuated LD was 19 kb, and 4 signal sites significantly associated with the flowering schedule type were obtained. Functional annotation was performed on related genes in a certain region upstream and downstream of the physical location of the four associated candidate sites, and 9 candidate transcripts related to flowering time were screened. Further analysis revealed that 9 transcripts contained a total of 4 candidate genes, which were homologous genes of Arabidopsis LOL1, CAT5 and FAD8. The results of this study could provide some theoretical basis and clues for obtaining candidate genes related to flowering time of B. campestris and using them to regulate flowering and genetic improvement.